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Firefox for iOS codebeat badge codecov

Download on the App Store.

This branch (main)

This branch works with Xcode 14.3.0, Swift 5.8 and supports iOS 14 and above.

Please note: Both Intel and M1 macs are supported 🎉 and we use swift package manager.

Please make sure you aim your pull requests in the right direction.

For bug fixes and features for a specific release, use the version branch.

Getting involved

We encourage you to participate in this open source project. We love Pull Requests, Issue Reports, Feature Requests or any kind of positive contribution. Please read the Mozilla Community Participation Guidelines and our Firefox for iOS contributing guidelines first.

Want to contribute on the codebase but don't know where to start? Here is a list of issues that are contributor friendly.

Building the code

  1. Install the latest Xcode developer tools from Apple.
  2. Install, Brew, Node, and a Python3 virtualenv for localization scripts:
    brew update
    brew install node
    pip3 install virtualenv
  3. Clone the repository:
    git clone
  4. Install Node.js dependencies, build user scripts and update content blocker:
    cd firefox-ios
    sh ./
  5. Open Client.xcodeproj in Xcode.
  6. Make sure to select the Fennec scheme in Xcode.
  7. Select the destination device you want to build on.
  8. Run the app with Cmd + R or by pressing the build and run button.

⚠️ Important: In case you have dependencies issues with SPM, please try the following:

  • Xcode -> File -> Packages -> Reset Package Caches

Building User Scripts

User Scripts (JavaScript injected into the WKWebView) are compiled, concatenated, and minified using webpack. User Scripts to be aggregated are placed in the following directories:

|-- /Frontend
    |-- /UserContent
        |-- /UserScripts
            |-- /AllFrames
            |   |-- /AtDocumentEnd
            |   |-- /AtDocumentStart
            |-- /MainFrame
                |-- /AtDocumentEnd
                |-- /AtDocumentStart

This reduces the total possible number of User Scripts down to four. The compiled output from concatenating and minifying the User Scripts placed in these folders resides in /Client/Assets and are named accordingly:

  • AllFramesAtDocumentEnd.js
  • AllFramesAtDocumentStart.js
  • MainFrameAtDocumentEnd.js
  • MainFrameAtDocumentStart.js

To simplify the build process, these compiled files are checked-in to this repository. When adding or editing User Scripts, these files can be re-compiled with webpack manually. This requires Node.js to be installed, and all required npm packages can be installed by running npm install in the project's root directory. User Scripts can be compiled by running the following npm command in the root directory of the project:

npm run build


This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at